DESCRIPTION

In its first form, the command provides the content or the type of an object in
the repository. The type is required unless -t or -p is used to find the
object type, or -s is used to find the object size, or --textconv or
--filters is used (which imply type "blob").

In the second form, a list of objects (separated by linefeeds) is provided on
stdin, and the SHA-1, type, and size of each object is printed on stdout. The
output format can be overridden using the optional <format> argument. If
either --textconv or --filters was specified, the input is expected to
list the object names followed by the path name, separated by a single
whitespace, so that the appropriate drivers can be determined.

OPTIONS

<object>

The name of the object to show.
For a more complete list of ways to spell object names, see
the "SPECIFYING REVISIONS" section in gitrevisions[7].

-t

Instead of the content, show the object type identified by
<object>.

-s

Instead of the content, show the object size identified by
<object>.

-e

Exit with zero status if <object> exists and is a valid
object. If <object> is of an invalid format exit with non-zero and
emits an error on stderr.

-p

Pretty-print the contents of <object> based on its type.

<type>

Typically this matches the real type of <object> but asking
for a type that can trivially be dereferenced from the given
<object> is also permitted. An example is to ask for a
"tree" with <object> being a commit object that contains it,
or to ask for a "blob" with <object> being a tag object that
points at it.

--textconv

Show the content as transformed by a textconv filter. In this case,
<object> has to be of the form <tree-ish>:<path>, or :<path> in
order to apply the filter to the content recorded in the index at
<path>.

--filters

Show the content as converted by the filters configured in
the current working tree for the given <path> (i.e. smudge filters,
end-of-line conversion, etc). In this case, <object> has to be of
the form <tree-ish>:<path>, or :<path>.

--path=<path>

For use with --textconv or --filters, to allow specifying an object
name and a path separately, e.g. when it is difficult to figure out
the revision from which the blob came.

--batch

--batch=<format>

Print object information and contents for each object provided
on stdin. May not be combined with any other options or arguments
except --textconv or --filters, in which case the input lines
also need to specify the path, separated by whitespace. See the
section BATCH OUTPUT below for details.

--batch-check

--batch-check=<format>

Print object information for each object provided on stdin. May
not be combined with any other options or arguments except
--textconv or --filters, in which case the input lines also
need to specify the path, separated by whitespace. See the
section BATCH OUTPUT below for details.

--batch-all-objects

Instead of reading a list of objects on stdin, perform the
requested batch operation on all objects in the repository and
any alternate object stores (not just reachable objects).
Requires --batch or --batch-check be specified. Note that
the objects are visited in order sorted by their hashes.

--buffer

Normally batch output is flushed after each object is output, so
that a process can interactively read and write from
cat-file. With this option, the output uses normal stdio
buffering; this is much more efficient when invoking
--batch-check on a large number of objects.

--unordered

When --batch-all-objects is in use, visit objects in an
order which may be more efficient for accessing the object
contents than hash order. The exact details of the order are
unspecified, but if you do not require a specific order, this
should generally result in faster output, especially with
--batch. Note that cat-file will still show each object
only once, even if it is stored multiple times in the
repository.

--allow-unknown-type

Allow -s or -t to query broken/corrupt objects of unknown type.

--follow-symlinks

With --batch or --batch-check, follow symlinks inside the
repository when requesting objects with extended SHA-1
expressions of the form tree-ish:path-in-tree. Instead of
providing output about the link itself, provide output about
the linked-to object. If a symlink points outside the
tree-ish (e.g. a link to /foo or a root-level link to ../foo),
the portion of the link which is outside the tree will be
printed.

This option does not (currently) work correctly when an object in the
index is specified (e.g. :link instead of HEAD:link) rather than
one in the tree.

This option cannot (currently) be used unless --batch or
--batch-check is used.

For example, consider a git repository containing:

f: a file containing "hello\n"
link: a symlink to f
dir/link: a symlink to ../f
plink: a symlink to ../f
alink: a symlink to /etc/passwd

For a regular file f, echo HEAD:f | git cat-file --batch would print

ce013625030ba8dba906f756967f9e9ca394464a blob 6

And echo HEAD:link | git cat-file --batch --follow-symlinks would
print the same thing, as would HEAD:dir/link, as they both point at
HEAD:f.

Without --follow-symlinks, these would print data about the symlink
itself. In the case of HEAD:link, you would see

4d1ae35ba2c8ec712fa2a379db44ad639ca277bd blob 1

Both plink and alink point outside the tree, so they would
respectively print:

symlink 4
../f

symlink 11
/etc/passwd

OUTPUT

If -t is specified, one of the <type>.

If -s is specified, the size of the <object> in bytes.

If -e is specified, no output, unless the <object> is malformed.

If -p is specified, the contents of <object> are pretty-printed.

If <type> is specified, the raw (though uncompressed) contents of the <object>
will be returned.

BATCH OUTPUT

If --batch or --batch-check is given, cat-file will read objects
from stdin, one per line, and print information about them. By default,
the whole line is considered as an object, as if it were fed to
git-rev-parse[1].

You can specify the information shown for each object by using a custom
<format>. The <format> is copied literally to stdout for each
object, with placeholders of the form %(atom) expanded, followed by a
newline. The available atoms are:

objectname

The 40-hex object name of the object.

objecttype

The type of the object (the same as cat-file -t reports).

objectsize

The size, in bytes, of the object (the same as cat-file -s
reports).

objectsize:disk

The size, in bytes, that the object takes up on disk. See the
note about on-disk sizes in the CAVEATS section below.

deltabase

If the object is stored as a delta on-disk, this expands to the
40-hex sha1 of the delta base object. Otherwise, expands to the
null sha1 (40 zeroes). See CAVEATS below.

rest

If this atom is used in the output string, input lines are split
at the first whitespace boundary. All characters before that
whitespace are considered to be the object name; characters
after that first run of whitespace (i.e., the "rest" of the
line) are output in place of the %(rest) atom.

If no format is specified, the default format is %(objectname)
%(objecttype) %(objectsize).

If --batch is specified, the object information is followed by the
object contents (consisting of %(objectsize) bytes), followed by a
newline.

For example, --batch without a custom format would produce:

<sha1> SP <type> SP <size> LF
<contents> LF

Whereas --batch-check='%(objectname) %(objecttype)' would produce:

<sha1> SP <type> LF

If a name is specified on stdin that cannot be resolved to an object in
the repository, then cat-file will ignore any custom format and print:

<object> SP missing LF

If a name is specified that might refer to more than one object (an ambiguous short sha), then cat-file will ignore any custom format and print:

<object> SP ambiguous LF

If --follow-symlinks is used, and a symlink in the repository points
outside the repository, then cat-file will ignore any custom format
and print:

symlink SP <size> LF
<symlink> LF

The symlink will either be absolute (beginning with a /), or relative
to the tree root. For instance, if dir/link points to ../../foo, then
<symlink> will be ../foo. <size> is the size of the symlink in bytes.

If --follow-symlinks is used, the following error messages will be
displayed:

<object> SP missing LF

is printed when the initial symlink requested does not exist.

dangling SP <size> LF
<object> LF

is printed when the initial symlink exists, but something that
it (transitive-of) points to does not.

loop SP <size> LF
<object> LF

is printed for symlink loops (or any symlinks that
require more than 40 link resolutions to resolve).

notdir SP <size> LF
<object> LF

is printed when, during symlink resolution, a file is used as a
directory name.

CAVEATS

Note that the sizes of objects on disk are reported accurately, but care
should be taken in drawing conclusions about which refs or objects are
responsible for disk usage. The size of a packed non-delta object may be
much larger than the size of objects which delta against it, but the
choice of which object is the base and which is the delta is arbitrary
and is subject to change during a repack.

Note also that multiple copies of an object may be present in the object
database; in this case, it is undefined which copy’s size or delta base
will be reported.